Art such as U.S. Pat. Nos. 3,892,958, C. Tung, July 11, 1975 and 3,967,273, H. Knowlton, June 29, 1976; and European Patent Application 11, 307, filed Nov. 19, 1979 all related to the multiple use of keyboard keys for reducing the number of keys required on a keyboard for processing data. This is particularly desirable for hand carried portable alphanumeric computer systems now feasible in the art, which are capable of processing many input characters and of internally processing many algebraic and data processing functions. Both numerics and alphabets are required in the present state of the art for communication, calculating and data processing operations of the type performed in portable hand held keyboard actuated computers.
The knowlton patent reduces the number of keys required in a telephone instrument for alphanumeric transmission capabilities to twelve by requiring two successive choices of tone signals for every entry digit such as numeral 2 or letter k. The Tung patent reduces in a computer-keyboard system the number of keys by providing three functions for designated keys with two sets of alternative functions chosen by respective orange or blue prefix keys. Thus, a calculator with thirty-two keys can be used for about three times that many functional computer entries including instructions and data. This latter concept is used, for example, in "Hewlett-Packard" Model HP-41 type programmable calculators with full alphanumeric capabilities. Similarly "Texas Instruments" TI-88 line of programmable calculators have alphabetic capabilities with two keyboard functions selectable, plus an alphabetic entry mode.
The general state of the art of calculator systems with complex many functional capacity is represented by U.S. Pat. No. 3,863,060 to F. Rode et al., Jan. 28, 1975.
The state of prior art portable hand held keyboard operated computers have still required excessive keys and have made alpha character entries awkward and time consuming. Also many prior art calculators have introduced alpha capabilities at the expense of utilizing 26 or more separate keys for the alphabet, sometimes using typewriter-like keyboards.
It is therefore an objective of this invention to provide improved alphanumeric entries with corresponding internal operational processing capabilities in hand held keyboard entry computer systems, and in particular to overcome deficiencies of the prior art. Other objects, features and advantages will be found throughout the following description, drawing and claims.